ES2204536T3 - HIGH RESISTANCE POLYETHYLENE FIBER AND ITS USE. - Google Patents

Abstract

A ballistic material comprising high strength polyethylene fibers   in which the fiber is characterized in that: it contains a high molecular weight polyethylene consisting essentially of a repeating unit of ethylene; it has an intrinsic viscosity number of 5 or larger and an average strength of 22 cN/dtex or higher; and the measurement of the fiber by differential scanning calorimetry (DSC) exhibits a temperature-increasing DCS curve having at least one endothermic peak over a temperature region of 140°C to 148°C (on the low temperature side) and at least one endothermic peak over a temperature region of 148°C or higher (on the high temperature side) or the number of frictions until the fiber is broken in an abrasion test according to method B for measuring abrasion resistance in the Testing Methods for Spun Yarn (JIS L 1095) is 100,000 or larger.

Description

High strength polyethylene fiber and its utilization.

The present invention relates to fibers Novelties of high resistance polyethylene and its applications. More particularly, it refers to high polyethylene fibers resistance that can be widely used in various fields industrial, for example, as cut fibers or fiber for produce nonwoven fabrics or spun strands or as fibers of reinforcement for composite materials such as concrete or fiber reinforced helmets.

For example they have been described for the fibers of high strength polyethylene, in the document JP-B 60-47922, high fibers module and high strength, produced by the "spinning method per gel "using ultra high molecular weight polyethylene as base material. These high strength polyethylene fibers They have already been widely used in various industrial fields, for for example, as ropes or nets for industrial or private use; as high performance textiles such as materials or ballistic components or protective gloves; or as networks geo-textiles or work, in the field of civil engineering and architecture.

In recent years, these polyethylene fibers high strength have needed additional performance improved, particularly in relation to its durability, for example, mechanical durability over a long period of time, or its adaptability under severe service conditions. Even textiles, such as sportswear, or fishing gear have required to have durability when used for a long time time frame. Additionally, reinforcing plates or ends to offer earthquake resistance have required to have durability, particularly fatigue resistance to bending or resistance against abrasion, so that when rolled around pillars or other parts, do not cause breakage of fiber in the corners.

High strength polyethylene fibers they effectively have excellent tensile strength and a Young's excellent module, but on the other hand, the structure of its molecular chains, very oriented, is responsible for inconvenience of having low durability, particularly little flexural fatigue resistance and poor resistance to abrasion, for example, compared to polyester or nylon for normal clothes. Such inconvenience has become a obstacle to the wide applicability of polyethylene fibers High strength in various industrial fields.

Additionally, many attempts have been made of using high strength polyethylene fibers in processes chemicals, for example, their application to nonwoven fabrics such as chemical filters or battery cell separators due to their excellent resistance to chemicals, light and the environment, or to apply high strength polyethylene fibers such as reinforcement fibers in concrete or cement, because it has emerged a demand for fiber reinforced concrete products with high  cracking resistance and high toughness as per a excellent impact resistance and excellent long durability term, since accidents have occurred due to detachment of materials from walls or falls from the surface of tunnels of railway or bridges

However, when cut fibers or fiber are  produced by cutting conventional polyethylene fibers, of high resistance, fiber fibrillation or high hardness surface is responsible for the inconvenience that these fibers are adhere to each other by pressure, forming a bundle of fibers that They lack dispersibility. Additionally, when used as reinforcing fibers for concrete or cement, their dispersibility in the cement matrix deteriorates due to bending or due to fiber entanglement For this reason, they have needed various treatments, for example, a premixed with cement, a hydrophilic treatment using metal oxides or agglomerated with resin.

To remedy such inconveniences, the orientation of the extended molecular chains of polyethylene They should be more relaxed. However, this method causes a low resistance and Young's modulus, and therefore cannot Being Employed. In addition, polyethylene fibers do not have a strong interaction between molecular chains and cause easily repeated fatigue fibrillation, which makes very difficult to improve the durability of these fibers.

Consequently, an objective of the present invention is to offer high strength polyethylene fibers and their applications, said fibers having approximately the same or Greater strength and Young's modulus than polyethylene fibers Conventional high strength. They also have an excellent flexural fatigue resistance and excellent resistance to abrasion and hardly cause fibrillation, and moreover, they have great Surface hardness.

That is, the present invention relates to High strength polyethylene fibers, characterized in that: the fiber comprises a high molecular weight polyethylene that essentially it consists of a repetitive unit of ethylene; have an intrinsic viscosity number of 5 or greater, and a resistance average of 22 cN / dtex or greater; and fiber measurement by differential scanning calorimetry (DSC) shows a DCS curve of temperature rise with at least one endothermic peak in a range from 140 ° C to 148 ° C (on the low temperature side) and at least one endothermic peak in a temperature range of 148 ° C or higher (on the high temperature side).

The present invention further relates to fibers made of high strength polyethylene characterized by: the fiber it comprises a high molecular weight polyethylene that essentially it consists of a repetitive unit of ethylene; has a number of intrinsic viscosity of 5 or greater and an average resistance of 22 cN / dtex or greater; and the number of frictions until the breakage of the fiber in an abrasion test according to method B to measure the abrasion resistance in the document "Test Methods of Spun Strands "(JIS L 1095) is 100,000 or greater.

The present invention relates more in addition to staple fibers, concrete products reinforced with fiber, helmets and other products obtained from previously indicated high polyethylene fibers resistance.

Figure 1 shows a DSC curve increasing temperature obtained by differential scanning calorimetry (DSC) of the high strength polyethylene fiber of Example 1.

Figure 2 shows a DSC curve for increasing temperature obtained by differential scanning calorimetry (DSC) of the high strength polyethylene fiber of the Example two.

Figure 3 shows a DSC curve of increasing temperature obtained by differential scanning calorimetry (DSC) of the high strength polyethylene fiber of the Example 3.

Figure 4 shows a DSC curve for increasing temperature obtained by differential scanning calorimetry (DSC) of the high strength polyethylene fiber of the Example Comparative 1.

Figure 5 shows a DSC curve of increasing temperature obtained by differential scanning calorimetry (DSC) of the high strength polyethylene fiber of the Example Comparative 2.

The high strength polyethylene fibers of the present invention are composed of a high polyethylene molecular weight consisting essentially of a repetitive unit of ethylene. As used in this document, the expression "High molecular weight polyethylene essentially consisting of a repeating unit of ethylene ”refers to a polyethylene that can be considered essentially as a ethylene homo-polymer containing a unit repetitive ethylene in a ratio of 99.5 mol% or greater, preferably 99.8 mol% or greater, and having a number of intrinsic viscosity of 5 or more, preferably 8 or more, and more preferably 10 or more. In order to increase the speed of polymerization, or in order to improve creep and other characteristics of the fibers finally obtained, it is recommended the introduction of ramifications into polyethylene by adding co-polymerizable monomers such as α-olefine in very small amounts. Without However, larger amounts of monomers are not preferred. co-polymerizable to improve the durability of the fibers, because it is assumed, for example, that the co-polymerization with α-olefins prevents mutual slippage between the molecular chains in the crystals, which it is impossible to get stress relief for continuous deformation repetition If the base polymer has a number of intrinsic viscosity less than 5, it is difficult to exhibit the mechanical characteristics of the fibers, particularly the tensile strength. On the other hand, there is no limit higher than the intrinsic viscosity number. Nevertheless, considering stability and productivity in the process of strand construction, fiber and other durability factors, it is preferable that the intrinsic viscosity number be 30 or less For example, the numbers of higher intrinsic viscosity of 30 may cause for example, reduced durability in some cases, depending on the lengthening conditions for spun strands

Consequently, the polyethylene fibers of high strength of the present invention, composed of a high molecular weight polyethylene which essentially consists of a repetitive unit of ethylene, have a viscosity number intrinsic of 5 or greater. As used in this document, the intrinsic viscosity number of the fibers refers to a value  corresponding obtained by measuring viscosity in decalin at a temperature of 135 ° C and extrapolation of η_ {sp} / c (where η_ {sp} is specific viscosity and c one concentration) towards zero concentration. In specific cases, viscosity measurement is performed in some concentrations and a straight line is drawn on the viscosity plot specific η sp against the concentration c by least square method and extrapolated to zero concentration to determine an intrinsic viscosity number.

Additionally, high weight polyethylene molecular, as the base polymer, is not especially limited, provided that the fibers finally obtained comply with the previous one  intrinsic viscosity number. To improve the durability of fibers to its limit, the use of a base polymer with a more narrowly distributed molecular weight. The use of a base polymer with an index (Mw / Mn) of molecular weight distribution of 5 or less, obtaining said polymer using a polymerization catalyst such as example, a metallocene catalyst.

The high strength polyethylene fibers of The present invention has an average resistance of 22 cN / dtex or higher. As used herein, the average resistance is refers to an average resistance value (cN / dtex) obtained drawing a stress strain curve using a machine tensile tests under the conditions: length of the specimen, 200 mm (gap distance between mounting): speed of elongation, 100% / min. : ambient temperature, 20 ° C; and humidity relative, 65%; and the calculation from the tension at the breaking point on the curve obtained (number of measurements, 10).

For high polyethylene fibers resistance of the present invention, its measurement by differential scanning calorimetry (DSC) shows a DCS curve of temperature rise with at least one endothermic peak in a range from 140 ° C to 148 ° C (on the low side temperature) and at least one endothermic peak in a range of temperature of 148 ° C or higher (on the high temperature side). The DSC temperature rise curve is obtained using a fiber specimen, which have been cut in lengths of 5 mm or shorter, keeping the specimen in a completely free state under an atmosphere of inert gas, and heating the specimen from ambient temperature up to 200 ° C with a heating rate from 10 ° C / min. For endothermic peaks, only peaks are used whose temperatures can be read, and the DSC curve is corrected increased to the baseline, followed by reading the peak temperatures and peak altitude. Is according used in this document, the baseline refers to a part of the DSC curve in the temperature range where transition does not occur no reaction in the test specimen, as defined in the document "Test Methods for Transition Temperatures of Plastics "(JIS K 7121). The peak altitude refers to the distance measured vertically to the axis of the abscissa between a line  interposed base and peak crest. In the document "Methods Test for Transition Temperatures of Plastics "(JIS K 7121), the peak is defined as part of a DSC curve where the curve leave the baseline and then return to the same baseline. In the present invention, when the DSC curve increases temperature obtained is differentiated (ie the first one is drawn derivative curve) and the derivative value (i.e. distance measured vertically to the axis of the abscissa between the first curve derivative and the axis of the abscissa, the value of the derivative has a plus - minus sign if the curve is above or below the axis of the abscissa, respectively) changes its sign from more to less, said part of the curve is defined as peak, and the part of the curve where the derivative value 1 changes since the increase monotonous to the decrease of the monotone, while maintaining its sign more or less, it is defined as shoulder. Of this definition it turns out, for example, that the DSC curve shown in Figure 2 has two peaks and the DSC curve shown in Figure 4 has a peak and a shoulder.

So, the JP-A 63-275708 describes high polyethylene fibers resistance obtained by a special technique using copolymerization with α-olefins, 1 and describes that when these fibers are wrapped around a bat of aluminum to be placed under restrictive conditions under tension and to then they are subjected to measurement by differential calorimetry Scanning (DSC) two or more peaks are observed, on the side of high temperature, arising from copolymerization, in addition to main peak However it is well known that when the fibers of high strength polyethylene under these conditions Restrictive under tension are subjected to measurement by DSC. Generally, this causes an increase in the melting point, or in some cases, the creation of two or more peaks produced by the crystalline transition or other factors.

On the contrary, the polyethylene fibers of high strength of the present invention are comprised of a polyethylene that can be considered essentially as a ethylene homopolymer, and measured by calorimetry differential scanning (DSC) in the present invention is performed using a fiber specimen that has been cut in lengths 5 mm or less and keeping the specimen in a fully state free. As it is known by the inventors, it has not been realized no report in the past concerning polyethylene fibers of high resistance that shows, even in that case, two or more endothermic peaks on the high temperature side. The reason for that the two or more endothermic peaks occur on the side of high temperature, even in that state of total freedom it seems be the presence of a high temperature crystalline structure 5 and type of merger (hereinafter referred to as "HMC") other than normal polyethylene crystal (hereinafter referred to as "EC"). As shown in the Examples, results are obtained favorable when structural formation is achieved with an i more positive removal of solvents contained on the surface of fiber Therefore, it can be assumed that the HMC is preferably formed on the surface layer of the fibers when the HMC layer has the function of maintaining resistance of the fibers and is a factor in the expression of resistance extremely excellent flexural fatigue and resistance Extremely excellent abrasion. It is also considered that the  excellent abrasion resistance prevents fibrillation and shape the fiber surface with a higher hardness.

JP-A 61-289111 describes medium stretched strands obtained by the method of spinning using two types of special solvents and describes that your DSC curves drawn by measurements in "free state" They have two or more endothermic peaks. Although there is no way to find out, unless it is by conjecture, what is this "state free ", it is well known that two or more endothermic peaks can often be observed even when there are fibers that have not been cut short but inserted in an aluminum plate to be measured, because, although you can say that these fibers are in a freer state than in normal measurements with fibers wrapped around a small piece of aluminum, the fibers in the plate are partially fixed between the bottom and the plate cover or uneven distribution of tension occurs through the test tube. To avoid such influence on the measurements, the specimen should be cut carefully in very short lengths as it has been made by the present inventors. Even if the measures described in the previous publication is the same as those of the present invention, the temperature range of the peaks endothermic described in the previous publication is different from the of the present invention, it is assumed for the following reason that stretched strands described therein have little resistance to flexural fatigue and poor abrasion resistance. While Therefore, with the production method described in the previous publication, that is, a slow technique in which the first and second solvents are substantially removed right after of spinning, it is quite difficult to offer a compact structure to The fiber surface.

As described above, for the fibers of high strength polyethylene of the present invention, the DSC curve of temperature rise in it has at least one endothermic peak in a temperature range of 140 ° C to 148 ° C. Particularly, said peak is preferably the main peak corresponding to the highest value of heat flow between two or more endothermic peaks found in the DSC curve of increased temperature. The main peak is supposed to reflect the structure normal (EC) that occupies most of the fibers and if the peak temperature thereof is less than 140 ° C the fibers have insufficient thermal resistance. In contrast, if the their peak temperature is above 148 ° C the Normal fiber structure becomes very restrictive, for example, an aggregate of fully extended chains; lowering the fiber durability. The present inventors have discovered that the durability of the fibers, particularly the resistance to flexural fatigue in this case becomes optimal when it appears the main peak in a temperature range of 140 ° C to 148 ° C.

For high polyethylene fibers resistance of the present invention, the DSC curve of increasing their temperature has at least one endothermic peak in a temperature range of 148 ° C or higher (on the high side temperature). It is assumed that this endothermic peak on the side of high temperature corresponds to the HMC structure that has a large influence on durability, particularly on abrasion resistance, of which will be described hereinafter, the training mechanism; and the fibers that shows no spikes endothermic on the high temperature side have a Extremely deteriorated abrasion resistance.

As described above, it is assumed that the  maximum endothermic peak on the high temperature side between two or more endothermic peaks found in the DSC curves of increased High strength polyethylene fiber temperature of the The present invention is derived from the HMC structure. Adjusting the altitude of this maximum endothermic peak on the high side temperature is possible to obtain polyethylene fibers of High strength with optimal durability.

In general, fiber fatigue molecularly oriented, typical examples of which are High strength polyethylene fibers, from bending or friction, is mainly caused by the fibrillation of the fibers from the surface layer. It is assumed that the fibers of high strength polyethylene of the present invention have the surface layer of HMC with more tangled molecular chains, what which results in a structure that hardly causes fibrillation, therefore the most compact surface structure makes that the fibers have excellent fatigue resistance due to flexion and abrasion resistance, preventing the fibers from adhere by pressure when cut.

However, it is important that the fibers of high strength polyethylene of the present invention have a particular relationship of HMC that occupies the entire crystalline structure. As described above, the maximum peak is assumed endothermic on the high temperature side is derived from the fusion of EC and the maximum endothermic peak on the low temperature side It is derived from the fusion of HMC. The altitude ratio of these maximum endothermic peaks in the respective temperature ranges It is generally in the range of 1.4: 1.0 to 3.0; 1.0 preferably 1.5, 1.0 to 2.9: 1.0 and more preferably 1.6; 1.0 to 2.8; 1.0. If the ratio is less than 1.4: 1.0, that is, if the maximum peak endothermic on the high temperature side is relatively higher, this means that the ratio of HMC that forms the surface layer of the fibers is greater, which lowers the durability of the fibers. This is probably due to an excessive increase in hardness Superficial causes deterioration, such as fatigue by buckling On the contrary, if the ratio is greater than 3.0: 1.0, that is, if the maximum endothermic peak on the high side temperature is relatively low, the ratio of HMC is lower, what which is not problematic in relation to resistance or the module of  Young but also does not improve durability, so that the fibers cannot avoid adhering by pressure when cut, making impossible to obtain cut fibers with good dispersibility

Additionally, the surface HMC structure, according to the present invention it is very effective for the improvement of impact resistence. To obtain high impact resistance, they require fibers with high strength and a high degree of elongation in deformation at high deformation speed, what That is called tenacity. The surface HMC structure according to the The present invention has the function of improving both of these features. From the point of view of the properties visco-elastic, polymeric materials can be considered as a combination of elastic components and viscous components as explained by what is called the model Takayanagi In the case of deformation at a high speed of deformation, viscosity characteristics have a large contribution, and surface HMC structure, according to the present invention shows a response to high strain strain in viscosity characteristics, making improvement possible of impact resistance. Therefore, polyethylene fibers high strength of the present invention with said resistance Enhanced to impact are suitable for materials or components ballistic or as reinforcement fibers of helmets.

Consequently, the polyethylene fibers of high strength of the present invention have durability markedly improved, particularly resistance to abrasion, compared to high polyethylene fibers conventional resistance. More specifically, the number of friction until the fiber breaks during a test to the abrasion, according to method B to measure abrasion resistance in the document "Test Methods for Spun Strands" (JIS L 1095) is 100,000 or greater.

The high strength polyethylene fibers of the present invention should be deliberately produced by a novel production method, for example, the method described to continuation that is recommended, although of course it will not be limiting to it.

First, a molecular weight polyethylene  high as described above dissolves evenly in a solvent to give a spinning solution. The solution of spinning has a general concentration of 50% or lower, preferably 30% or lower. The solvent may include volatile solvents such as decalin and tetralin and non-volatile solvents such as paraffin oil or paraffin wax. The use of volatile solvents is preferred. This  it is because for solvents that are in solid state or non-volatile at normal temperature, the speed of solvent extraction from filaments is slow and therefore it is difficult to get a sufficient formation of HMC while volatile solvents on the fiber surface are positively evaporated in the yarn to offer a higher concentration on the fiber surface, making possible the formation of a specific crystalline structure (HMC) in which the molecular chains are more highly oriented and connected to each other. In the case of spinning techniques conventional, a structural difference between the surface of the fiber and the interior is responsible for the decrease in fiber resistance; the selection of the conditions of spinning to make the sectional structure of the fibers the most possible uniform is therefore a general knowledge for people with normal knowledge in the art, not only of spinning by gel but also dry spinning, wet spinning and melt spinning of polyvinyl alcohol and polyacrylonitrile, by example, that is to say in the spinning technique in general.

On the contrary, the present inventors have discovered that the formation of a structural difference between the fiber surface and inside in the spinning step, more specifically the formation of HMC by instant elimination and solvent-positive on the fiber surface for con this concentrates the tension of the yarn on the surface layer, makes it possible to obtain fibers that maintain a high strength and a high Young's modulus and also have excellent  flexural fatigue resistance and excellent resistance to abrasion

In the production of high polyethylene fibers  resistance of the present invention, a technique is recommended to blow an inert gas at high temperature on the filaments discharged just below the spinner for disposal positive of the solvents on the surface of the filaments. The result is the formation of a very thin layer of HMC on the surface to therefore concentrate the tension of the yarn, making possible the formation of a specific structure in the which molecular chains are connected to each other as  described above. The inert gas temperature is generally 60 ° C or higher, preferably 80 ° C or greater, and more preferably 100 ° C or higher but below 150 ° C. For inert gas, the use of nitrogen gas is preferred from the economic point of view but it is not limiting to it.

The unstretched filaments obtained from this form are reheated to remove the remaining solvents, during which, they are stretched at a rate of several times. In Depending on the situation, several stretching can be used Steps. The HMC structure of the surface layer formed in the spinning can never be removed in subsequent steps of stretching, making it possible to obtain fibers from high strength polyethylene with extremely features excellent as described above. Fibers of High strength polyethylene obtained, practically no adhere due to the cut pressure, even if they are cut, because they have a compact surface structure, even said phenomenon of adhesion of fibers in fibers is observed  conventional; therefore you can get cut fibers or fiber with good dispersibility.

The high strength polyethylene fibers of The present invention has excellent fatigue resistance by bending and excellent abrasion resistance, while having approximately the same or greater resistance and Young's modulus than those of high strength polyethylene fibers conventional; therefore high polyethylene fibers resistance of the present invention are suitable for various ropes or cables for industrial or private use, especially drag cables used for a long period of time, such as ropes and bows, ropes of Blinds; printing cables; and are equally useful as materials for various sports teams and sportswear, such as fishing tackle, tents, socks sports and uniforms, as well as various clothing items. The high strength polyethylene fibers of the present invention They are also extremely useful for high performance textiles such as ballistic materials or components or gloves protection, due to its excellent cut resistance and excellent resistance to cuts by blades that are the result of previous excellent features. Polyethylene fibers  high strength of the present invention are additionally useful in chemical processes due to its compact surface and consequently having a marked improvement in resistance to chemicals, light and the environment, compared to conventional ultralight molecular weight polyethylene fibers, for example as the fibers cut to produce nonwoven fabrics such as chemical filters or battery separators batteries, which require resistance to chemicals. The high strength polyethylene fibers of the present invention they are additionally useful as reinforcing fibers in materials compounds for sports equipment such as helmets and skis and speaker cones for speakers, such as reinforcement for concrete or mortar, particularly in concrete applied by simple and normal gun or concrete in tunnels, or as fibers for reinforcing plates and ends that offer resistance against earthquakes

Now, among the applications of the fibers of high strength polyethylene of the present invention, in later, cut fibers and concrete products with reinforcing fibers, in particular.

High polyethylene cut fibers resistance of the present invention can be obtained from the previous novel high-strength polyethylene fibers and the amount of poorly dispersed fibers (diameter fiber mallets maximum 40 µm or greater, formed by adhering by pressure or fusion) found in the case of papermaking is preferably 5% or less. If the number of mallets of fiber of maximum diameter 40 µm or greater, is greater than 5% of weight, uneven suction may occur that forms spots when water is sucked under reduced pressure during the process of wet manufacturing of nonwoven fabrics. Spotting is responsible for the deterioration in resistance, in resistance to cuts by blades and other characteristics of nonwoven fabrics. The linear density of the mono filament of the cut fibers is not particularly limiting, but is generally in the range of 0.1 to 20 dpf. You can change depending on the applications, for example, those of higher linear density are used as reinforcing fibers for concrete or cement, and for normal nonwoven fabrics; and the of lower linear density are used for nonwoven fabrics of high density such as chemical filters or separators battery cells The length of the cut fibers, that is the cut length of the fibers, is preferably 70 mm or more short, more preferably 50 mm or shorter. This is due to that if the cut length is too long the fibers can easily cause tangles which hinders their uniformity of dispersion. In addition, the fiber cutting method may include, but not be particularly limited to those of the guillotine type or of the type cut by rotation.

High polyethylene cut fibers strength of the present invention are useful as fibers cut to produce nonwoven fabrics such as filters chemicals, battery cell separators, sheet metal water screening for chemicals; as fibers of concrete or cement reinforcement; and as a fiber to produce feather blankets or spun strands, due to their excellent resistance to chemicals, light and the environment.

Concrete products with fiber reinforcement of the present invention can be produced using the previous high strength polyethylene novel fibers such as reinforcing fibers The reinforcing fibers have excellent shear strength, probably due to its surface compact, and when dispersed in a cement matrix almost no cause fiber flexion and show good properties of dispersion in the cement matrix. The reinforcing fibers have an additionally improved resistance to chemicals, to light and the environment due to its compact surface compared to conventional high strength polyethylene fibers and are the most suitable as reinforcing fibers, particularly for concrete or cement that require chemical resistance against the alkaline properties of cement. Therefore, the products of concrete with reinforcing fibers of the present invention show good qualities in service of its production and have a improved performance, such as compressive strength, resistance to bending and toughness and also have excellent impact resistance and excellent durability.

Examples

The present invention will be additionally represented with some examples; however, the present The invention is not limited to these examples.

First, the polyethylene fibers of High strength of the present invention are shown as an example in Examples 1 to 3 and Comparative Examples 1 to 2. Fibers of polyethylene prepared according to these Examples and Examples Comparatives were measured to check their physical properties by the following measurement methods and tests, and evaluated To check your performance.

Number of intrinsic viscosity of the fibers

Using a viscosity test tube capillary of the Ubbelohde type, diluted solutions of different concentrations to check the viscosity in decalin at a temperature of 135 ° C, and the viscosity number was determined intrinsic by drawing a straight line on the graph of your specific viscosity against concentrations by the method of least squares and extrapolation of the straight line towards the zero concentration During the viscosity measurement, it was cut a test piece of approximately 5 mm in length, and a antioxidant (with the trade name of "Yoshino BHT" from Yoshitomi Pharmaceutical Industries Ltd) in 1 wt% relative to the test tube, followed by stirring at a temperature of 135 ° C for 4 hours until its dissolution to offer a solution of measurement.

Strength and Young's modulus of fibers

A strain strain curve was drawn using “Tensilon” of Orientech Corp., under the conditions: specimen length, 200 mm (distance between mandrel fasteners); elongation speed, 100% / min .; ambient temperature, 20 ° C; and relative humidity, 65%; and the resistance (cN / dtex) of the tension at the breaking point on the curve obtained and calculated Young's modulus (cN / dtex) of the tangential line that offers the maximum gradient over the curve near the origin. The number of measurements was set at 10, and resistance was expressed and Young's module with the respective mean values.

Differential scanning calorimetry (DSC) of the fibers

Using "DSC7" of Perkin-Elmer Corp. (maximum sensitivity 8 µW / cm), a DSC was performed as follows. He cut one specimen of 5 mm or less and approximately 5 mg of the specimen was loaded and sealed in an aluminum plate. This same dish of Aluminum, although empty, was used as a reference. It was drawn a DSC temperature rise curve by heating the specimen from  ambient temperature up to 200 ° C at a heating rate 10 ° C / min, under an inert gas atmosphere. The DSC curve of temperature rise obtained was corrected for the baseline, followed by a reading of the number of peaks, the temperatures of peaks and peak altitudes in a temperature range from 140 ° C to 148 ° C (on the low temperature side) and in a range of temperature of 148 ° C or higher (on the high temperature side), and calculating the ratio of the maximum endothermic peak altitude in the low temperature side and the maximum endothermic peak on the side high temperature If the reading of the endothermic peaks It is difficult due to its shoulder-like shapes, the values of heat flux at 145.5 ° C and 150 ° C are considered as peaks endothermic on the low temperature side and on the high side temperature respectively, to calculate the ratio of peak altitudes.

Fiber abrasion tests

A test tube was prepared by multiplication or adjustment, to obtain a linear density of approximately 1500 dtex and abrasion resistance was evaluated by a test to abrasion according to method B to measure resistance to abrasion in the document "Test Methods for Spun Strands (JIS L 1095) ". Using a tip of 0.9 mm \ diameter of hard steel as friction contact, each test was performed under the following conditions: load, 0.5 g / d; friction speed, 115 times / min .; reciprocal movement distance, 2.5 cm; and angle of friction, 110 °. The abrasion resistance was determined as the number of frictions until the test piece breaks. The number of passes was set at 2 and the result was expressed by Your average values. The values were rounded up to a third digit.

Example 1

A 10 wt% slurry mixture of polyethylene from ultra high molecular weight with an intrinsic viscosity number of 21.0 and an index (Mw / Mn) of molecular weight distribution of 3.7 and 90 wt% decalin was fed to a type mixer nut at a temperature of 230 ° C, and its dissolution was achieved to offer a spinning solution, followed by spinning at a discharge speed through each nozzle of 1.4 g / min, using a spinner (the diameter of each nozzle, 0.7 mm; the number of nozzles, 400), at a temperature of 170 ° C Discharged filaments were blown with nitrogen gas at 100 ° C so more uniformly possible at an average flow rate of 1.2 m / sec., through a slit-shaped hole for gas supply, said hole being located just by under the spinner, so that the decalin on the surface of The fiber was positively evaporated. Immediately after, the filaments were substantially cooled with air flow to 30 ° C, and rolled at a speed of 75 m / min. by type rollers Nelson arranged spinning down. At that time, the solvent content in the filaments had already reduced their weight in half from its original weight. Next, the filaments obtained they were stretched in a ratio of 4 in a heating oven at 100 ° C and additionally stretched in a ratio of 4 in an oven heating at 149 ° C, thus obtaining a fiber of polyethylene. The evaluation of physical properties and the Fiber performance are shown in Table 1. The DSC curve of temperature rise before baseline correction that was obtained by differential scanning calorimetry (DSC) it shown in Figure 1.

Example 2

A polyethylene fiber thereof was prepared. form described in Example 1, with the exception that Discharged filaments were blown with nitrogen gas at 120 ° C at an average flow rate of 1.4 m / sec. The evaluations of the Physical properties and fiber performance are shown in the Table 1. The DSC curve of temperature rise before the correction of the baseline that was obtained by calorimetry Differential scanning (DSC) is shown in Figure 2.

Example 3

A polyethylene fiber was prepared therein. form described in Example 1, with the exception that a high molecular weight polyethylene with a viscosity number intrinsic of 12.1 and an index (Mw / Mn) of weight distribution Molecular 5.4 was used; the concentration of a solution of spinning was set at 30 wt%; and stretching was done with a ratio of 3 during the first stage and 2.2 in the second stage. The evaluation of physical properties and performance of the fiber are shown in Table 1. The DSC curve of increasing temperature before the baseline correction, which was obtained by differential scanning calorimetry (DSC) shown in Figure 3.

Comparative Example one

A polyethylene fiber thereof was prepared. form described in Example 1, with the exception that downloaded filaments were not blown just below the spinning machine with high temperature nitrogen gas, but they were immediately cooled with nitrogen gas at 30 ° C; and the stretching with a ratio of 4.0 during the first stage and of 3.5 during the second stage. The evaluation of the properties Physical and fiber performance are shown in Table 1. The DSC temperature rise curve before the correction of the baseline, which was obtained by differential calorimetry of Sweep (DSC) is shown in Figure 4.

Comparative Example two

Spinning was performed in the same way as described in Example 1, except that oil was used paraffin as solvent; and stretching was performed with a ratio of 4, while the solvent was substantially extracted in a cooling bath containing η-decane at about 80 ° C, said Bathroom arranged just below the spinner. It was not performed No positive cooling with inert gas. Semi filaments obtained stretches were further stretched with a ratio of 4 in an oven at 145 ° C under an inert gas atmosphere, so that the η-decane content was substantially evaporated, thus obtaining a fiber of polyethylene. The evaluation of physical properties and the Fiber performance are shown in Table 1, the DSC curve of temperature rise before baseline correction, which was obtained by differential scanning calorimetry (DSC) it shown in Figure 5.

one

As can be seen in Table 1, the fibers of polyethylene of Examples 1 to 3 had excellent abrasion resistance due to its 3.5 times greater number of friction until fiber breakage in the abrasion test, while showing approximately the same or greater resistance and Young's modulus compared to polyethylene fibers that Comparative Examples 1 to 2. For polyethylene fibers of Examples 1 to 3, the DSC temperature rise curves had one or more endothermic peaks on the high temperature side and a endothermic peak on the low temperature side. Conversely, for the polyethylene fiber of Comparative Example 1, the curve DSC temperature rise had no endothermic peak on the side low temperature, while no clear peak was found, except one shoulder as an endothermic peak on the high side temperature. For the polyethylene fiber of the Comparative Example 2, the DSC temperature rise curve had a full peak in the high temperature side, while no endothermic peak it was observed except a small shoulder of 133 ° C on the low side temperature. For the polyethylene fibers of the Examples Comparatives 1 and 2 assume that their maximum endothermic peaks in the high temperature side comes from EC and not from HMC due to its  Extremely deteriorated abrasion resistance.

Now, the high polyethylene cut fibers  resistance of the present invention are shown as an example by Examples 4 to 8 and Comparative Examples 3 to 5. The cut fibers prepared in these Examples and Examples Comparatives were evaluated to determine their performance through the Next test method.

Dispersibility test of cut fibers

First, 0.02 g of fibers were weighed cut, they were introduced in a test tube containing 300 ml of water  distilled, and stirred 50 times with a glass rod. The Cut fibers were then collected by filtration with a fine mesh so that they could not pass through it, They were then air dried for 24 hours. Then fiber mallets formed by pressure adhesion or Fusion were extracted to be observed with a magnifying glass. Mallets fiber were measured to check their low diameter microscope, and fiber mallets with a maximum diameter of 40 µm or higher (slightly dispersed fibers) were measured to check their weight total. Additionally, the weight was measured, including that of the cut fibers with good dispersibility, and the poorly dispersed fiber content (percentage of failure of dispersion). In this essay, it seems that the results vary widely; consequently the number of passes was set at 10 and the results were expressed by their average values.

Example 4

High strength polyethylene fibers prepared in Example 1 (intrinsic viscosity number 18.6, linear density, 455 dtex, resistance, 38.1 cN / dtec; module Young, 1521 cN / dtex) were cut in 10 mm sizes by the guillotine method to provide cut fibers. The Evaluation of their performance is shown in Table 2.

Example 5

High strength polyethylene fibers prepared in Example 2 (intrinsic viscosity number, 18.4; linear density 448 dtex; resistance, 35.2 cN / dtec; module Young, 1612 cN / dtex) were cut into 10 mm pieces by the guillotine method to provide cut fibers. The Evaluation of their performance is shown in Table 2.

Example 6

High strength polyethylene fibers prepared in Example 3 (intrinsic viscosity number, 9.4; linear density 1150 dtex; resistance 28.5 cN / dtec; Module Young, 1055 cN / dtex) were cut into 10 mm pieces by the guillotine method to provide cut fibers. The Evaluation of their performance is shown in Table 2.

Example 7

A polyethylene fiber thereof was prepared. form described in Example 1, with the exception that a spinner (diameter of each nozzle, 0.2 mm; number of nozzles, 200) was used and the download speed through each nozzle was set at 0.08 g / min. For the fiber obtained, the intrinsic viscosity number was 18.5, the linear density was 240 dtex, the linear density of the monofilament was 0.12 dtex, the resistance was 33.6 cN / dtex, Young's modulus was 1342 cN / dtex, the number of frictions until fiber breakage during the friction test was 103,000 and the DSC curve increased temperature obtained by differential scanning calorimetry (DSC) had an endothermic peak on the low temperature side and two endothermic peaks on the high temperature side, the maximum endothermic peak temperature 144.7 ° C on the low side temperature and 159.2 ° C on the high temperature side, and the height ratio of the maximum endothermic peaks 2.4: 1. This fiber was cut into 50 mm pieces by the method of guillotine to provide cut fibers. The evaluation of your. Performance is shown in Table 2.

Example 8

A polyethylene fiber was prepared from same way as described in Example 1, with the exception of that a high molecular weight polyethylene with a intrinsic viscosity number of 10 and an index (Mw / Mn) of 5.4 molecular weight distribution; the concentration of a spinning solution was set at 30 wt%; one was used spinning machine (with diameter of each nozzle of 0.2 mm, number of nozzles, 200); and download speed through each nozzle was set at 0.08 g / min. For the fiber obtained, the intrinsic viscosity number was 9.4; linear density was 1265 dtex, the linear density of the mono filament was 0.63 dtex, the resistance was 25.2 cN / dtex, Young's module was 931 cN / dtex, the number of frictions until fiber breakage during the test to the abrasion was 161,000 and the DSC curve of temperature rise obtained by differential scanning calorimetry (DSC) had an endothermic peak on the low temperature side and two peaks endothermic on the high temperature side, the temperature being of the maximum endothermic peak 143.9 ° C on the low temperature side and 154.9 ° C on the high temperature side, and the ratio of the altitude of the maximum endothermic peaks 2.2: 1. This fiber is cut into 10 mm pieces by the guillotine method to Provide cut fibers. The evaluation of their performance is shown in Table 2.

Comparative Example 3

High strength polyethylene fibers prepared in Comparative Example 1 (viscosity number intrinsic, 18.4; linear density, 541 dtex; resistance, 34.2 cN / dtc; Young's module, 1516 cN / dtex) were cut into pieces of 10 mm by the guillotine method to provide fibers cut. the evaluation of its performance is shown in the Table two.

Comparative Example 4

High strength polyethylene fibers prepared in comparative example 2 (viscosity number intrinsic, 18.3; linear density, 471 dtex; resistance 335.7 cN / dtec; Young's module, 1623 cN / dtex) were cut into pieces 10 mm by the guillotine method to provide fibers cut. The evaluation of its performance is shown in the Table two.

Comparative Example 5

A polyethylene fiber thereof was prepared. such as described in Example 1, with the exception that used paraffin oil as a solvent and the filament was stretched at a ratio of 4 in a heating oven at 100 ° C and then at a ratio of 4 in a heating oven to 149 ° C. For the fiber obtained, the intrinsic viscosity number it was 18.5, the linear density was 455 dtex, the linear density monofilament was 1.2 dtex, the resistance was 38.1 cN / dtex, the Young's module was 1521 cN / dtex, the number of frictions up to fiber break during the abrasion test was 421,000 and the DSC temperature rise curve obtained by calorimetry sweep differential (DSC) had an endothermic peak on the side Low temperature and two endothermic peaks on the high side temperature, the maximum endothermic peak temperature being 144.3 ° C on the low temperature side and 152.1 ° C on the high side  temperature, and the peak altitude ratio being maximum endothermic 2,4: 1. This fiber was cut into pieces of 80 mm by the guillotine method to provide cut fibers. The evaluation of its performance is shown in Table 2.

two

As can be seen from Table 2, the fibers cut from Examples 4 to 8 show little dispersion failure and therefore they had excellent dispersibility compared to the cut fibers of Comparative Examples 3 to 5.

Therefore, reinforced cement products fiber using high strength polyethylene fibers of the present invention are shown as an example by Examples 9 to 11 and Comparative Examples 6 to 8. The test specimens of Cement test prepared in these Examples and Examples Comparatives were evaluated to demonstrate their performance through The next resistance test.

Resistance test of cement test specimens

In the compression test, the maximum load was measure to determine the compressive strength. In the trial at flexion, the maximum load was measured to determine the flexural strength according to the method for mediating resistance to flexion in the document "Physical Test Methods for Cement (JIS R 5201) "For tenacity, the relationship between load and displacement of the head in the test machine was registered in an X-Y register (of Yokogawa Electric Corporation) and the area under the curve of bending, tension of flexion, until it was determined the displacement that fell until 50% of the value at the maximum load, and the toughness was considered as a relationship of the area with the area in case of not considering No fiber incorporation like 1.

Example 9

High strength polyethylene fiber prepared in Example 1 (intrinsic viscosity number, 18.5; linear density 455 dtex; resistance, 38.1 cN / dtex; module Young, 1521 cN / dtex) was cut into 30 mm length pieces and used as reinforcement fibers. First, cement Portland high and early resistance, high (specific gravity, 3.13) Toyoura-kelsa sand (standard old sand; specific gravity, 2.7) as aggregates and fumes of silica (specific gravity, 2.2) as added mineral were introduced in an omni-mixer of 5 L volume and mixed dry for 15 seconds. The previous reinforcing fibers were then introduced into the mixer, and to then dry mixed for another 30 seconds. Drag of water and air and a high-ranking water reducing agent (without incorporation of auxiliary air drag agents) were introduced into the mixer, then mixed for 4 minutes to provide fiber reinforced concrete. The Binder water ratio was set at 33%; the proportion of mixed silica fume relative to the weight of the cement, at 10%; the binder sand ratio, at 60%; the mixing ratio of air drag and high relative range water reducing agent to the weight of the agglomerate, in 2.0%, and the mixing ratio of the  fiber by volume, at 2.0%. The measured flow values are shown in Table 5.

Using fiber reinforced concrete obtained, three cylindrical test specimens were prepared (50 mm \ diameter x 100 mm) for the compression test and three prismatic test specimens (40 x 40 x 160mm) for the test of flexion, placing them manually with a mallet and a trowel. The specimens obtained in this way were subjected to a cure standard for 14 days before the resistance test. The Results are shown in Table 5.

Example 10

A reinforced concrete specimen was prepared of fiber in the same manner described in Example 9, with the except that the prepared high polyethylene fiber was used in Example 2 (intrinsic viscosity number, 18.4; density linear, 448 dtex; resistance, 35.2 cN / dtec; Young's module, 1612 cN / dtex) and then underwent resistance testing. The results are shown in Table 3.

Example 11

A reinforced concrete specimen was prepared of fiber in the same manner described in Example 9, with the except that high polyethylene fiber was used resistance, prepared in Example 3 (viscosity number intrinsic, 9.4; linear density, 1150 dtex; resistance, 28.5 cN / dtec; Young's module, 1055 cN / dtex) and then it was submitted to the resistance test. The results are shown in the Table 2.

Comparative Example 6

A reinforced concrete specimen was prepared of fiber in the same manner described in Example 9, with the except that high polyethylene fiber was used resistance, prepared in Comparative Example 1 (number of intrinsic viscosity, 18.4; linear density, 541 dtex; resistance, 34.2 cN / dtec; Young's module, 1516 cN / dtex) and a He was then subjected to the resistance test. The results They are shown in Table 3.

Comparative example 7

A reinforced concrete specimen was prepared of fiber in the same manner described in Example 9, with the except that high polyethylene fiber was used resistance, prepared in Comparative Example 2 (number of intrinsic viscosity, 18.3; linear density, 471 dtex; resistance, 35.7 cN / dtec; Young's module, 1623 cN / dtex) and a He was then subjected to the resistance test. The results They are shown in Table 3.

Comparative example 8

A reinforced concrete specimen was prepared of fiber in the same manner described in Example 9, with the except that no reinforcing fiber was used; already He was then subjected to the resistance test. The results They are shown in Table 3.

3

As can be seen in Table 3, the test tubes of examples 9 to 11 show a greater resistance to compression, greater resistance to bending, and greater toughness; therefore, they had excellent impact resistance and excellent durability compared to the test specimens of the Examples Comparisons 6 to 8.

Industrial Applicability

According to the present invention, they can be obtained high strength polyethylene fibers with approximately the same or greater strength and Young's modulus than those of the fibers Conventional high-strength polyethylene, and at the same weather have excellent durability, particularly resistance to flexural fatigue and excellent abrasion resistance. These high strength polyethylene fibers can be applied widely in various fields, for example, as staple fibers or fiber to produce nonwoven fabrics or non-spun strands; or as reinforcing fibers for composite materials such as concrete products and fiber reinforced helmets.

Claims (9)

1. A high strength polyethylene fiber characterized in that the fiber comprises a high molecular weight polyethylene essentially consisting of a repetitive unit of ethylene; it has an intrinsic viscosity number of 5 or greater and an average resistance of 22 cN / dtex or greater, and the measurement of the fiber by differential scanning calorimetry (DSC) shows a DSC curve of temperature increase with at least one endothermic peak in a temperature range of 140 ° C to 148 ° C (on the low temperature side) and at least one endothermic peak in a temperature range of 148 ° C or higher (on the high temperature side). 2. High strength polyethylene fiber according to claim 1, wherein the height ratio of the maximum endothermic peak on the low temperature side and the peak maximum endothermic on the high temperature side is 1.4: 1.0 a 3.0: 1.0. 3. High strength polyethylene fiber according to claim 2, wherein the height ratio of the maximum endothermic peak on the low temperature side and the peak endothermic maximum on the high temperature side is 1.5: 1.0 a 2.9: 1.0. 4. A high strength polyethylene fiber characterized in that the fiber comprises a high molecular weight polyethylene essentially consisting of a repetitive unit of ethylene; it has an intrinsic viscosity number of 5 or greater and an average resistance of 22 cN / dtex or greater; and the number of frictions until fiber breakage in an abrasion test according to method B to measure abrasion resistance in Spinning Thread Test Methods (JIS L 1095) is 100,000. 5. A high cut polyethylene fiber strength obtained from high strength polyethylene fiber according to claim 1 or 4. 6. High cut polyethylene fiber resistance according to claim 5, wherein the amount of sparse fibers (fiber mallets with a maximum diameter of 40 µm or greater formed by adhesion due to pressure or fusion) Found in the case of paper production is 5% by weight or less. 7. High polyethylene cut fiber strength according to claim 5, wherein the fiber has a cutting length of 70 mm or shorter. 8. A concrete product with fiber reinforcement comprising the high strength polyethylene fiber according to the claim 1 or 4. 9. A helmet that comprises the fiber of high strength polyethylene according to claim 1 or 4.